Assay products and procedures

Abstract

In cytometry and like procedures, the number of different types of identifiable particle (and, therefore, the number of detectable analytes) is increased by using the coding labels on some particles as signal labels on other particles, and by using the signal labels on some particles as coding labels on other particles. In one such procedure, the particles of a first class are coded with preselected amounts of a first pair of fluorochromes, and the particles of a second class of particles are coded with preselected amounts of a second pair of fluorochromes. The analytes which interact with the first class of particles are identified by a signal label selected from the second pair; and the analytes which interact with a second class of particles are identified by a signal label selected from the first pair.

What is claimed is:  
     
         1 . A composition which is suitable for use as a reagent in assaying a sample, the composition comprising a plurality of particles, each of the particles 
 (i) having a coding characteristic,    (ii) containing analyte-interaction sites, and    (iii) belonging to one only of a plurality of defined categories, and each of the particles in each defined category    (a) having the same coding characteristic, the coding characteristic being provided by a single coding label in a preselected amount or by two or more coding labels in preselected amounts, the coding label or labels being selected from a group of at least n labels, where n is at least 3, all of the labels being capable of being assessed in the same way, the number of coding labels on each particle being at most (n−1), and each of the labels in the group being a coding label in at least one of the defined categories, and    (c) containing the same analyte-interaction sites; ps the combination of the coding characteristic and the analyte-interaction sites on the particles in each category being different from the combination of the coding characteristic and the analyte-interaction sites in all the other categories.    
     
     
         2 . A composition according to  claim 1  wherein n is 4.  
     
     
         3 . A composition according to  claim 2  wherein each of the particles belongs to a first class (AB) or to a second class (XY), 
 each of the particles of class AB belonging to one of two or more subclasses (AB 1 , AB 2  . . . AB n ), 
 each of the particles in each subclass AB 1 , AB 2  . . . AB n  being coded by at least one of a first label A and a second label B, the amounts of the labels A and B being such that the particles of each sub class can be distinguished from the particles of the other subclasses AB 1 , AB 2  . . . AB n , 
 each of the particles in each subclass AB 1 , AB 2  . . . AB n  belonging to one of two subsubclasses (AB 1X , AB 1Y ), (AB 2X , AB 2Y ) . . . (AB nX , AB nY ), and  
 
 
 each of the particles of class XY belonging to one of two or more subclasses (XY 1 , XY 2  . . . XY n ), 
 each of the particles in each subclass XY 1 , XY 2  . . . XY n  being coded by at least one of a third label X and a fourth label Y, the amounts of the labels X and Y being such that the particles in each sub class can be distinguished from the particles of the other subclasses XY 1 , XY 2  . . . XY n ; 
 each of the particles in each subclass XY 1 , XY 2  . . . XY n  belonging to one of two subsubclasses (XY 1A , XY 1B ), (XY 2A , XY 2B ) . . . (XY nA , XY nB ),  
 
 
 the analyte-interaction sites contained by the particles in each of the subsubclasses (AB 1X , AB 1Y ), (AB 2X , AB 2Y ) . . . (AB nX , AB nY ) and (XY 1A , XY 1B ), (XY 2A , XY 2B ) . . . (XY nA , XY nB ), being different from the analyte-interaction sites contained by the particles in the other subsubclasses.  
 
     
     
         4 . A composition according to  claim 3  wherein each of the labels is a fluorochrome.  
     
     
         5 . A composition according to  claim 3  wherein each of the particles is a single assay particle.  
     
     
         6 . A composition according to  claim 3  wherein some of the particles are dual assay particles and the remainder are single assay particles.  
     
     
         7 . A composition which is a precursor for a composition according to  claim 1  and which is the same as said composition except that at least some of the particles contain, in place of the analyte-interaction sites, precursors for the analyte-interaction sites.  
     
     
         8 . A composition which can be examined in a cytometer or like instrument, the composition comprising a plurality of particles, each of the particles 
 (i) having a coding characteristic,    (ii) containing analyte-interaction sites and/or corresponding sites which are the same as said analyte-interaction sites except that they have interacted with one or more analytes, and    (iii) belonging to one only of a plurality of defined categories, each of the particles in each defined category    (a) having the same coding characteristic, the coding characteristic being provided by a single coding label in a preselected amount or by two or more coding labels in preselected amounts, the coding label or labels being selected from a group of at least n labels, where n is at least 3, all of the labels being capable of being assessed in the same way, the number of coding labels on each particle being at most (n−1), and each of the labels in the group being a coding label in at least one of the defined categories, and    (b) containing the same analyte-interaction sites and/or corresponding sites which have interacted with one or more analytes;    the combination of the coding characteristic and the analyte-interaction sites and/or corresponding sites on the particles in each category being different from combination of the coding characteristic and the analyte-interaction sites and/or corresponding sites on the particles in all the other categories; and    the particles in at least one of the categories containing analyte-interaction sites which have interacted with one or more analytes and which are associated with a signal label which (i) is selected from the group of at least n labels and (ii) is not one of the labels which provides the coding characteristic for the particle containing the interacted site.    
     
     
         9 . A composition according to  claim 8  wherein n is 4.  
     
     
         10 . A composition according to  claim 9  which is the same as a composition as defined in  claim 3  except that analyte-interaction sites on the particles in at least one of the subsubclasses have interacted with one or more analytes, and those interacted sites are associated with a signal label which is 
 (i) for the analyte-interaction sites on the particles of class AB, the third label X for one of the subsubclasses of each subclass and the fourth label Y for the other of the subsubclasses of that subclass, and  
 (ii) for the analyte-interaction sites on the particles of class XY, the first label A for one of the subsubclasses of each subclass and the second label B for the other of the subsubclasses of each subclass;  
 
     
     
         11 . A composition according to  claim 10  wherein each of the labels is a fluorochrome.  
     
     
         12 . A composition according to  claim 10  wherein each of the particles is a single assay particle.  
     
     
         13 . A composition according to  claim 10  wherein some of the particles are dual assay particles and the remainder are single assay particles.  
     
     
         14 . A method of analyzing a sample to ascertain whether it contains possible analytes, the method comprising 
 (A) contacting the sample with a composition according to  claim 1;     (B) before, during or after step (A), carrying out a treatment which results in the association of a signal label with the sites which have interacted with one or more analytes, the signal label (i) being selected from the group of at least n labels and (ii) not being one of the labels which provides the coding characteristic for the particles carrying the interacted sites; and    (C) after steps (A) and (B), identifying the coding and signal labels on each particle of a representative sample of the particles.    
     
     
         15 . A method according to  claim 14  wherein step (B) comprises 
 (B1) before, during or after step (A), carrying out a treatment which, for each of the possible analytes and group or groups of analytes, if present, results in the presence of a signal label as defined on analyte-interaction sites which have interacted with the analyte or one of the group or groups of analytes.  
 
     
     
         16 . A method according to  claim 14  wherein step (B) comprises 
 (B2) before, during or after step (A), contacting the sample, or the reagent, or the product of step (A), with a composition comprising an analog for each of the possible analytes or group of possible analytes, whereby analyte-interaction sites which have not interacted with the analytes interact with said analogs, and before, during or after said contacting, carrying out a treatment which, for each analog, results in the presence of a signal label as defined on the analyte-interaction sites which have interacted with one of the analogs.  
 
     
     
         17 . A method according to  claim 14  wherein n is 4, and each of the particles belongs to a first class (AB) or to a second class (XY), 
 each of the particles of class AB belonging to one of two or more subclasses (AB 1 , AB 2  . . . AB n ), 
 each of the particles in each subclass AB 1 , AB 2  . . . AB n  being coded by at least one of a first label A and a second label B, the amounts of the labels A and B being such that the particles of each sub class can be distinguished from the particles of the other subclasses AB 1 , AB 2  . . . AB n , 
 each of the particles in each subclass AB 1 , AB 2  . . . AB n  belonging to one of two subsubclasses (AB 1X , AB 1Y ), (AB 2X , AB 2Y ) . . . (AB nX , AB nY ), and  
 
 
 each of the particles of class XY belonging to one of two or more subclasses (XY 1 , XY 2  . . . XY n ), 
 each of the particles in each subclass XY 1 , XY 2  . . . XY n  being coded by at least one of a third label X and a fourth label Y, the amounts of the labels X and Y being such that the particles in each sub class can be distinguished from the particles of the other subclasses XY 1 , XY 2  . . . XY n ; 
 each of the particles in each subclass XY 1 , XY 2  . . . XY n  belonging to one of two subsubclasses (XY 1A , XY 1B ), (XY 2A , XY 2B ) . . . (XY nA , XY nB ),  
 
 
 the analyte-interaction sites contained by the particles in each of the subsubclasses (AB 1X , AB 1Y ), (AB 2X , AB 2Y ) . . . (AB nX , AB nY ) and (XY 1A , XY 1B ), (XY 2A , XY 2B ) . . . (XY nA , XY nB ), being different from the analyte-interaction sites contained by the particles in the other subsubclasses.  
 
     
     
         18 . A method according to  claim 17  wherein each of the labels is a fluorochrome, and some of the particles are dual assay particles and the remainder are single assay particles.  
     
     
         19 . A cytometer comprising a computer which is programmed so that the cytometer will examine a composition according to  claim 8  and produce an assay of the analytes which have interacted with the analyte-interaction sites.  
     
     
         20 . Software which can be installed on a computer controlling a cytometer so that the cytometer will examine a composition according to  claim 8  and produce an assay of the analytes which have interacted with the analyte-interaction sites.